In general, a functional film can be made on a process line by delivering an uncoated web material, applying a coating composition to the web material, and performing drying or other treatment steps to process the coating composition to form a coating layer on the web material. The coating composition is often not coated across the full width of the web material, and the uncoated margins are eventually cut off prior to winding up the coated web product.
Rollers can be utilized to convey the web material on the process line. Thin web substrate materials can be particularly difficult to transport over or between the rollers on the process line without causing wrinkles, kinks, bagginess, and the like, and such defects can significantly reduce the value of the coated web product. In addition, passing very thin or delicate coatings over and through rollers can damage the coating layer, which also reduces the value of the coated web product to a potential customer.
Reducing frictional force at an interface between the surface of the rollers and the surface of the web material can be helpful in reducing these types of defects. For example, reducing the tension on the web substrate material, changing the material on the surfaces of the rollers that contacts the web substrate (for example, using o-rings or sleeves on the contacting surfaces of the rollers), and reducing the wrap angle at which the web substrate contacts the roller have been employed.